This competing renewal of R01 CA119171, Nutrition and Physical Activity Assessment Study (NPAAS), continues to focus on the use of biomarkers to evaluate and compare measurement properties of prominent nutritional and physical activity assessment methods, and on the use of biomarker-calibrated nutrient consumption and activity-related energy expenditure (AREE) estimates in studies in Women's Health Initiative (WHI) cohorts of postmenopausal women. Our aims are: 1) To conduct a controlled feeding study to develop biomarkers for additional nutrients and foods, and 2) To use biomarkers from the ongoing and proposed NPAAS study phases to develop biomarker-calibrated nutrient consumption and AREE estimates, throughout the WHI cohorts for use in disease-association studies. We will recruit 150 women, in the age range 60-80 y, enrolled in the WHI Seattle Field Center, into a feeding study of a highly individualized controlled diet, with each woman's diet designed to approximate her usual food consumption patterns. Women will receive all foods and beverages during the 2-week feeding period. We will obtain 24-h urine-derived nutritional measures, including nitrogen (protein), fructose, sucrose (sugars), alkylresorcinols (whole grains) and 1- and 3- methylhistidine (meat); and blood-derived nutritional measures, including carotenoids (fruits & vegetables), 1- and 3 -tocopherols (fats & oils), phospholipid fatty acids (fats & oils), and folate (fruits & vegetables) at the beginning and end of the 2-week feeding period. Biomarker evaluation will include an assessment of the ability of urine and blood measures, and study subject characteristics to explain variation in nutrients and foods provided during the feeding study. Total energy expenditure (TEE) will be measured using a doubly-labeled water protocol, as will resting energy expenditure (REE) using indirect calorimetry with 0.9TEE-REE as objective measure of AREE. We will develop calibration equations for each nutrient/food or activity measure having a suitable biomarker, by regression analysis of the biomarker on corresponding self-report measures using specimens and data from the women in both NPAAS project phases. Suitable biomarkers will be available for total energy, protein, percent of energy from protein, and for total activity-related energy expenditure. We will apply these calibration equations in the WHI cohorts using a food-frequency questionnaire and multiple-day food record to produce calibrated consumption estimates and using a WHI activity questionnaire to produce calibrated AREE estimates. These calibrated estimates will be related to the subsequent incidence of a broad range of clinical outcomes (e.g., cancer, cardiovascular disease, diabetes, frailty, obesity, etc) among the 161,808 women in the WHI cohorts. This work addresses fundamental gaps in diet and physical activity epidemiology research, in the context of national and international obesity epidemics, and in much related chronic disease morbidity and mortality.